The mechanism by which "abrogation" of Fv-1 restriction occurs has been studied with the metabolic inhibitors cytosine arabinoside (AraC), which inhibits DNA synthesis, and cycloheximide, which inhibits protein synthesis. AraC did not inhibit abrogation although it effectively shut off DNA synthesis. This result, in agreement with other data from this laboratory, suggests that the viral function involved in "abrogation" is unique and distinct from those involved in productive infection. In addition, it has been shown that cycloheximide did not prevent abrogation in treated cells, suggesting that abrogation occurs in the absence of protein synthesis.